This application relates generally to gas turbine engine combustors and, more particularly, to combustor deflectors.
Combustors are used to ignite fuel and air mixtures in gas turbine engines. Known combustors include at least one dome attached to a liner defining a combustion zone. Fuel igniters are attached to the combustor in flow communication with the dome to supply fuel to the combustion zone. Fuel enters the combustor through a deflector attached to a spectacle plate. The deflectors prevents hot combustion gases produced within the combustion zone from impinging upon the spectacle plate.
Various types of deflectors are known and combustors typically include a plurality of deflectors. Known deflectors are rectangular-shaped and bordered with substantially square radial edges. The deflectors include a plurality of hemispherical projections to facilitate heat transfer from the deflector. The projections extend outward from the deflector and are hemispherical in shape. Known deflectors are typically fabricated from Mar-M-509, HS-188, or Hast-X materials to protect the dome from flame radiation. Such deflectors are also coated with an air plasma spray thermal barrier coating.
During operation, the deflector is subjected to extreme oxidation and low cycle fatigue, LCF, stresses as a result of exposure to flame radiation and hot combustion gases produced within the combustion zone. Over time, the thermal barrier coating covering the square radial edges disintegrates and exposes the deflector to potentially damaging hot temperatures and flame radiation. Such exposure may lead to oxidation and LCF cracking, eventual failures of the deflectors, and distress of the spectacle plates, thus, reducing a useful life of the combustor.
In an exemplary embodiment, a combustor for a gas turbine engine includes a deflector assembly that enhances heat transfer from the combustor and minimizes low cycle fatigue stresses induced within the combustor. The combustor deflector assembly includes a plurality of deflectors secured to a spectacle plate. Each deflector has tapered edges and includes a plurality of cylindrical projections extending outward to facilitate heat transfer from the combustor deflector during gas turbine engine operations. The projections include rounded edges and are arranged in a high density pattern. The deflector is coated with a thermal barrier coating and a bondcoat to minimize exposure of the deflector to hot combustion gases and flame radiation produced as a result of fuel burning in the combustor.
During gas turbine engine operation, the combination of the thermal barrier coating and the projections enhances heat transfer from the deflector plate. Such increased heat transfer facilitates reducing the temperature of the deflector, reducing oxidation, and reducing low cycle fatigue. Additionally the deflector is fabricated from a substrate alloy that further reduces oxidation.